dgit: Better error message if non-split-brain patch stack no longer applies

(due to new upstream version, or user messing with it). Closes:#833025.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

1 files changed, 11 insertions, 2 deletions

diff --git a/dgit b/dgit
index fa926dd..c1b1c25 100755
--- a/dgit
+++ b/dgit
@@ -4456,8 +4456,17 @@ sub quilt_fixup_multipatch ($$$) {
 
     ensuredir '.pc';
 
-    runcmd qw(sh -ec),
-        'exec dpkg-source --before-build . >/dev/null';
+    my @bbcmd = (qw(sh -ec), 'exec dpkg-source --before-build . >/dev/null');
+    $!=0; $?=-1;
+    if (system @bbcmd) {
+	failedcmd @bbcmd if $? < 0;
+	fail <<END;
+failed to apply your git tree's patch stack (from debian/patches/) to
+ the corresponding upstream tarball(s).  Your source tree and .orig
+ are probably too inconsistent.  dgit can only fix up certain kinds of
+ anomaly (depending on the quilt mode).  See --quilt= in dgit(1).
+END
+    }
 
     changedir '..';